The present invention is related to Japanese patent application No. Hei. 11-210909, filed Jul. 26, 1999; No. Hei. 11-298497, filed Oct. 20, 1999; No. 2000-116937, filed Apr. 18, 2000; No. 2000-148460, filed May 19, 2000; the contents of which are incorporated herein by reference.
The present invention relates to a heat-pump-type refrigeration-cycle device, and more particularly to a heat-pump-type refrigeration cycle device that changes between heating, cooling and dehumidifying modes.
In a vehicle such as an electric car, conventionally, since engine waste-heat (hot water) cannot be used as a heat source for heating a passenger compartment, a heat-pump-type refrigeration-cycle device is installed to heat the passenger compartment with refrigerant-condensation heat from a condenser. Here, an outdoor heat-exchanger is operated as an evaporator during lower-outside temperatures in winter. At that time, however, since heat-extraction by the outdoor heat exchanger is low, compressor-inhale refrigerant pressure is reduced. Therefore, the refrigerant specific-volume is increased, and refrigerant-cycle volume is decreased, thereby reducing heating performance. That is, cold-area operation has low heating performance for the passenger compartment.
In JP-A-9-328013 and JP-A-11-34640, therefore, the present applicant has proposed a refrigeration-cycle device that increases heating performance. In the refrigeration-cycle device, higher-pressure cycle-refrigerant is depressurized to intermediate pressure during heating. The intermediate-pressure refrigerant is separated into gas and liquid refrigerant by a gas-liquid separator. Then, the intermediate-pressure refrigerant is gas-injected into a compressor, while recovering the waste heat from heating devices mounted on a vehicle. This increases heating performance.
In the above-described devices, the waste heat from heating devices mounted on the vehicle is recovered by the intermediate-pressure refrigerant. For improving heating performance by gas-injection, however, the absolute pressure of the intermediate-pressure refrigerant is set to 5 kg f/cm2 or more and the temperature is set to 15xc2x0 C. or more. Therefore, when the temperature of the hot water (waste-heat recovering fluid) for extracting heat from the heating devices is lower, the temperature difference between the hot water and the intermediate-pressure refrigerant is insufficient, thereby making the waste-heat recovery impossible. Also, an evaporator for a refrigeration cycle is disposed upstream of an air duct of an indoor air-conditioner unit. A condenser is disposed at the downstream side thereof. With this arrangement, dehumidification is performed, thereby defrosting a windshield.
Also, in the above described prior art, the refrigerant-flow direction is changed so that gas refrigerant discharged from the compressor flows into an outdoor heat-exchanger during cooling and into an indoor condenser during heating, channeled by a four-way valve disposed on the compressor-discharge side. When the outdoor heat-exchanger is frosted during heating, the refrigerant-flow direction is reversed by the four-way valve creating a reverse cycle (cooling cycle). Accordingly, frost on the outdoor heat-exchanger is removed with heat from the higher-temperature gas refrigerant discharged from the compressor.
Since the outdoor heat exchanger is defrosted by the reversed cycle, indoor heating cannot be performed during defrosting. As such, the passenger compartment remains cold.
Also, since the four-way valve changes the operation mode to change the direction of refrigeration-flow, the refrigerant-piping structure of the cycle is complicated and the number of components such as check valves are increased. The present invention was developed in light of these drawbacks
In light of these and other aforementioned drawbacks, the present invention provides a gas-injection type refrigeration-cycle device having a heat-exchanging means where refrigerant extracts heat from a waste-heat recovering fluid which has recovered waste heat from heating device. Further, the operation mode of the present invention can be changed between a lower-pressure-side heat-extraction heat-pump mode, an intermediate-pressure-side heat-extraction heat-pup mode and a gas-injection heat-pump mode. In the lower-pressure-side heat-extraction heat-pump mode, the heat-exchanging means is set to a lower-pressure side, and the lower-pressure refrigerant drawn into the compressor extracts heat from the waste-heat recovering fluid. In the intermediate-pressure-side heat-extraction heat-pump mode, heat-exchanging means is set at an intermediate-pressure side, and the intermediate-pressure refrigerant introduced into compressor-gas-injection port extracts heat from the waste-heat recovering fluid. In the gas-injection heat-pump mode, heat extracted from the waste-heat recovering fluid is stopped, and the intermediate-pressure refrigerant is drawn into gas-injection port.
Since the refrigerant mode can be changed between the three heat-pump modes in this manner, the heat-pump mode is selected according to the temperature of the waste-heat recovering fluid and the amount of waste heat from heating device. Therefore, this preferable mode selection can make the waste-heat recovery from heating device effective, thereby preferably improving the heating performance over all ranges of waste-heat recovering fluid temperature and the amount of waste heat.
In another aspect of the invention, the refrigeration-cycle device has a condenser, for heating air with the gas refrigerant discharged from compressor and is disposed within air-conditioning duct. Evaporator, for cooling air, is disposed upstream of said condenser within air-conditioning duct. In the refrigeration-cycle device, the operation mode can be changed between a heating mode, a cooling mode and dehumidifying mode. During the heating mode, hot air heated by condenser is blown into a passenger compartment while outdoor heat-exchanger (24) operates as an evaporator. During the cooling mode, cool air cooled by evaporator is blown into the compartment while the heat exchanger operates as a condenser. During the dehumidifying mode, the air, cooled by evaporator and again heated by condenser, is blown into the compartment.
Furthermore, in the refrigeration-cycle device, when a defrosting mode for defrosting outdoor heat-exchanger is set to the heating mode, the gas refrigerant discharged from compressor is divided into two portions. One of the divided-refrigerant portions flows into outdoor heat-exchanger for defrosting and the other flows into evaporator to heat blown air within air-conditioning duct.
According to this manner, the passenger compartment can be heated by the air-heating operation of evaporator while outdoor heat-exchanger is defrosted. That is, when evaporator is not used for heating, evaporator is effectively utilized in the defrosting mode, thereby ensuring indoor-heating during the defrosting mode without complicating the refrigeration cycle.
In the present invention, the refrigeration-cycle device further includes first heat-exchanger for recovering the waste heat from heating device. In the defrosting mode, the waste heat from heating device is extracted by the refrigerant and provided to evaporator by first heat-exchanger.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.